When the Supreme Court struck down Texas's law against sodomy in the summer of 2003, in the landmark gay rights case of Lawrence v. Texas, critics warned that its sweeping
support of a powerful doctrine of privacy could lead to challenges of state laws that forbade such things as gay marriage and bigamy. "State laws against bigamy, same-sex marriage, adult incest, prostitution, masturbation, adultery, fornication, bestiality, and obscenity are ... called into question by today's decision," wrote Justice Antonin Scalia, in a withering dissent he read aloud page by page from the bench.

It turns out the critics were right. Plaintiffs have made the decision the centerpiece of attempts to defeat state bans on the sale of sex toys in Alabama, polygamy in Utah and adoptions by gay couples in Florida. So far the challenges have been unsuccessful. But plaintiffs are still trying, even using Lawrence to challenge laws against incest.

In Ohio, lawyers for a Cincinnati man convicted of incest for sleeping with his 22-year-old stepdaughter tell TIME that they will make the Lawrence decision the centerpiece of an appeal to the Supreme Court. "Our view of Lawrence is a fairly narrow one, that there is a Constitutional right under the 14th Amendment's due process clause that says private consensual activity between adults cannot be criminal," said J. Dean Carro, the lead lawyer for Paul D. Lowe, the former sheriff's deputy sentenced in 2004 to 120 days in jail after pleading no contest to incest.

But Houston lawyer Mitchell Katine, one of the attorneys who handled the Lawrence case before the Supreme Court, isn't so sure the court will agree. The state, he said, will likely argue that the intimate facts of family life in this case are different enough from the facts in the Lawrence case that Lawrence's privacy protection should not apply. "That's the hurdle they have to get over."

They have already failed to do so once. The Ohio Supreme Court rejected the plantiffs' argument that Lawrence created a new fundamental privacy right that made laws restricting consensual, private sex among adults unconstitutional. Instead, prosecutors successfully argued that Lawrence said only that anti-sodomy laws bore no rational relationship to a legitimate state interest  the lowest of Constitutional barriers. Agreeing, the Ohio Supreme Court ruled that state interests in preventing incest  even among adults or step-relations  were perfectly legitimate.

The issue does not appear to have been challenged in federal court previously, though the 7th Circuit Court of Appeals ruled in 2005 that a Wisconsin law forbidding incest among blood relations (but not including step-relations) did not conflict with Lawrence's ruling. But in upholding prison sentences for a brother-sister couple in that case, the court acknowledged that the language in Lawrence is all but certain to prompt more challenges to prosecutions for sex-related crimes on privacy grounds.

Katine said he hopes the muddied waters can be cleared up by the U.S. Supreme Court soon. "I really hope that the Court will take an issue and explain what they really meant."

Justice Anthony Kennedy's ruling in the Lawrence case was greeted enthusiastically by those who thought it would usher in a new era of privacy rights. But lower courts have been very careful about interpreting the decision. The 11th Circuit Court of Appeals, for instance, twice rejected efforts to broaden Lawrence. In 2004, it upheld Florida's law prohibiting gay adoptions by saying the importance of providing for children gives the state the right to set rules for their adoption. And later that year, it ruled that a district judge in Alabama had erred in using Lawrence to strike down the state's prohibition on the sale of sex toys. Only in Massachusetts, with its famous gay marriage decision handed down four months after Lawrence, has a top appeals court sided with plaintiffs seeking to use the decision to void state laws regarding sex or marriage.

"When we first read some of the language about dignity and how the state doesn't have a right to impose its moral code on its citizens, we thought this decision would be extremely powerful and widely followed," Katine told TIME. "I am disappointed that the lower courts have not followed some of the language that is contained in Lawrence."

If the Court declines to hear Lowe's case, others less fraught with taboo could take its place in seeking to define the reach of Lawrence. The ACLU has filed suit in several states to challenge the few remaining statutes that prohibit unmarried couples from living together. This is the sort of case that may have a better chance of expanding Lawrence's reach, said Katine.